Today, a wealth of information is published in web pages on the world-wide-web. Often, metadata, or data about the information that is itself published in web pages, is just as important as the published information itself. For example, metadata that indicates when a web page or information in the web page was first published can be just as important as the information itself. Regrettably, it is often difficult to determine when information in a web page was first published on the world-wide-web since the content of web page can change over time and the history of that content change is generally not recorded in the web page. As a result, unless the author of a web page maintains and publishes all previous versions of the page, a reader cannot usually determine whether the information in the page was published at the same time or whether different parts of the page were published at different times. In addition, a reader cannot usually determine when a given part or section of a web page was first published in the web page.
Some efforts have been made to date web pages. For example, some wiki-based websites allow users to see differences between different versions of a web page published on the wiki-based website. However, these websites only allow two versions of a web page to be compared, and the information on either version may have first been published in a third and earlier version of the page. Moreover, these websites are generally limited to comparing different versions of web pages that are published on their own website. They do not allow a user to compare or contrast different versions of arbitrary pages on the world-wide-web. Other websites do attempt to catalogue and store different versions of arbitrary pages published on the world-wide-web, however, these websites generally do not provide a convenient mechanism for automatically determining the changes that have been made to a web page as a function of time, or for automatically determining when a particular part of a web page was first added to the web page. In short, none of the existing efforts to date web pages allow a user to systematically determine when different parts of an arbitrary web page were first published on the world-wide-web.